diff options
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/memory.c | 36 |
1 files changed, 25 insertions, 11 deletions
diff --git a/mm/memory.c b/mm/memory.c index 5c694f2b9c12..9bdbd10cb418 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -108,7 +108,7 @@ static int __init disable_randmaps(char *s) } __setup("norandmaps", disable_randmaps); -static unsigned long zero_pfn __read_mostly; +unsigned long zero_pfn __read_mostly; /* * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init() @@ -455,6 +455,20 @@ static inline int is_cow_mapping(unsigned int flags) return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; } +#ifndef is_zero_pfn +static inline int is_zero_pfn(unsigned long pfn) +{ + return pfn == zero_pfn; +} +#endif + +#ifndef my_zero_pfn +static inline unsigned long my_zero_pfn(unsigned long addr) +{ + return zero_pfn; +} +#endif + /* * vm_normal_page -- This function gets the "struct page" associated with a pte. * @@ -512,7 +526,7 @@ struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, goto check_pfn; if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) return NULL; - if (pfn != zero_pfn) + if (!is_zero_pfn(pfn)) print_bad_pte(vma, addr, pte, NULL); return NULL; } @@ -534,6 +548,8 @@ struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, } } + if (is_zero_pfn(pfn)) + return NULL; check_pfn: if (unlikely(pfn > highest_memmap_pfn)) { print_bad_pte(vma, addr, pte, NULL); @@ -1161,7 +1177,7 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address, page = vm_normal_page(vma, address, pte); if (unlikely(!page)) { if ((flags & FOLL_DUMP) || - pte_pfn(pte) != zero_pfn) + !is_zero_pfn(pte_pfn(pte))) goto bad_page; page = pte_page(pte); } @@ -1443,10 +1459,6 @@ struct page *get_dump_page(unsigned long addr) if (__get_user_pages(current, current->mm, addr, 1, FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma) < 1) return NULL; - if (page == ZERO_PAGE(0)) { - page_cache_release(page); - return NULL; - } flush_cache_page(vma, addr, page_to_pfn(page)); return page; } @@ -1629,7 +1641,8 @@ int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr, * If we don't have pte special, then we have to use the pfn_valid() * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must* * refcount the page if pfn_valid is true (hence insert_page rather - * than insert_pfn). + * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP + * without pte special, it would there be refcounted as a normal page. */ if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) { struct page *page; @@ -2097,7 +2110,7 @@ gotten: if (unlikely(anon_vma_prepare(vma))) goto oom; - if (pte_pfn(orig_pte) == zero_pfn) { + if (is_zero_pfn(pte_pfn(orig_pte))) { new_page = alloc_zeroed_user_highpage_movable(vma, address); if (!new_page) goto oom; @@ -2658,8 +2671,9 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, spinlock_t *ptl; pte_t entry; - if (HAVE_PTE_SPECIAL && !(flags & FAULT_FLAG_WRITE)) { - entry = pte_mkspecial(pfn_pte(zero_pfn, vma->vm_page_prot)); + if (!(flags & FAULT_FLAG_WRITE)) { + entry = pte_mkspecial(pfn_pte(my_zero_pfn(address), + vma->vm_page_prot)); ptl = pte_lockptr(mm, pmd); spin_lock(ptl); if (!pte_none(*page_table)) |